With the recent advance of semiconductor technology, efforts are made in various ways to realize a micro-machine capable of considerable miniaturization with use of advanced semiconductor manufacturing technology, and electro-mechanical elements such as micro-actuators are now spotlighted. By using such elements, small-sized highly accurate mechanical components can be obtained, and productivity can be greatly improved by performing a semiconductor process. Particularly, micro-actuators using piezoelectric elements are used for fine displacement of a scanning tunneling microscope and for fine positioning of a head slider of a magnetic recording and reproducing disk device.
For example, in a magnetic recording and reproducing disk device, a magnetic head for recording and reproducing information on a magnetic disk is mounted on a head slider, and the head slider is fitted to an actuator arm. The actuator arm is oscillated by a voice coil motor (hereinafter called VCM), then the magnetic head is positioned to a predetermined track position on the magnetic disk to execute a recording or reproducing operation. However, with enhancement in recording density, using only such a conventional VCM is not enough to assure sufficient accuracy. Therefore, in addition to a VCM positioning device, a high-speed highly accurate positioning technology, in that a head slider is finely driven by a fine positioning device using piezoelectric elements, is proposed for example, extra-high TPI and piggyback actuator (IDEMA Japan News No.32, pp 4–7, issued by International Disk Drive Equipment Materials Association in Japan).
Thus, actuators using piezoelectric elements are expected to be employed for various purposes. Conventionally, a configuration multilayered by a green-sheet lamination method or thick film multilayer formation method has often been employed (for example, Japanese patent public presentation official report No. H6-224483). However, one layer of a piezoelectric element manufactured by such a manufacturing method is about 10 μm in thickness, requiring a driving voltage of about 100V.
On the other hand, in Japanese patent public presentation official report No. H8-88419 is disclosed a thin film laminate type actuator that is small-sized and can be driven by application of a low voltage and is large in an amount of displacement; its manufacturing method is also disclosed. That is, an electrode layer made of platinum, aluminum, gold or silver, a piezoelectric layer made from a piezoelectric material such as lead zirconate titanate (PZT) and lead lanthanum zirconate titanate (PLZT), and an electrode layer made from a material similar to the above materials are formed on a single-crystal substrate such as magnesium oxide, strontium titanate or sapphire. Further, a bonding layer consisting of glass or silicon is formed thereon in order to manufacture a piezoelectric member.
Next, piezoelectric members are bonded to each other via a bonding layer by performing an anode joining method, and after that, the substrate at a laminating side is removed by grinding or the like, and a bonding layer is formed on the electrode layer then exposed, and the bonding layer is bonded to a bonding layer of another piezoelectric member produced by the above-mentioned procedure, and a substrate is again removed. By repeating these steps, a laminate body with a plurality of laminated layers is formed. After that, inner electrodes in the laminate body are alternately extended from either side to achieve a laminate type actuator. During this manufacturing method, the substrate is removed by etching after grinding so that no residual portion is allowed to exist. Also, as a method of bonding piezoelectric members to each other, it is stated that a surface activation joining method or adhesive joining method can be employed besides an anode joining method.
However, in the above example, since an external electrode is formed via an insulating layer from two sides of a laminate body multilayered with piezoelectric members, it is necessary to form an external electrode for every individual laminate body, so that a problem of productivity arises. Also, since displacement takes place in a perpendicular direction to a substrate surface, the resulting configuration is not suitable, for example, for a structure used as a micro-actuator of a head slider of a magnetic recording and reproducing disk device.